Cigarette-dense-end-measuring method and apparatus

ABSTRACT

The location of dense tobacco regions relative to the ends of cut cigarettes is determined by a density gauge positioned adjacent to a moving tobacco rod prior to cutting in a cigarette making machine and located therein by means of a signal from the density gauge which is divided by an electronic gating circuit into two components, one representative of the density of that portion of the rod that will provide the ends of the cut cigarettes and the other representative of that portion of the rod that will lie intermediate the ends. The signal components are averaged and an output signal proportional to their difference is obtained to indicate correct synchronization of the cigarette cutter with the dense end device. Pulses from the cutter may be presented simultaneously on a dual channel oscilloscope with the density signal to visually indicate an outof-phase condition. Alternately, an out-of-phase condition may be indicated on a meter arranged in parallel with an alarm.

United States Patent [72] Inventor John E. De Witt Columbus, Ohio 121]App]. No. 864,292 {221 Filed Oct. 3, 1969 [45] Patented Sept. 14, 1971[73] Assignee Industrial Nucleonics Corporation Continuation ofapplication Ser. No, 544,000, Apr. 20, 1966.

{54] ClGARETTE-DENSE-END-MEASURING METHOD AND APPARATUS 19 Claims, 4Drawing Figs.

[52] US. Cl 131/21, 131/65, 131/84, 146/104 [51] 1nt.Cl A24c 5/18, A24c5/28 [50] Field 01 Search 131/21,21 B,21 D, 84, 84C, 61, 61 A,6113,63,64, 65; 146/1, 104

[5 6] References Cited UNITED STATES PATENTS 1,567,533 12/1925 131/651,851,334 3/1932 131/65 1,920,708 8/1933 131/65 1,968,018 7/1934 131/632,316,213 4/1943 l31/61UX 2,290,896 7/1942 131/61 B 2,338,070 12/1943Lopez 131/21UX 2,543,277 2/1951 Copeman 131/6 3 X PrimaryExaminer-Joseph S Reich Att0rneysWi1liam T. Fryer, 111, C. HenryPeterson and James J. OReilly ABSTRACT: The location of dense tobaccoregions relative to the ends of cut cigarettes is determined by adensity gauge positioned adjacent to a moving tobacco rod prior tocutting in a cigarette making machine and located therein by means of asignal from the density gauge which is divided by an electronic gatingcircuit into two components, one representative of the density of thatportion of the rod that will provide the ends of the cut cigarettes andthe other representative of that portion of the rod that will lieintermediate the ends. The signal components are averaged and an outputsignal propos= tional to their difference is obtained to indicatecorrect synchronization of the cigarette cutter with the dense enddevice. Pulses from the cutter may be presented simultaneously on a dualchannel oscilloscope with the density signal to visually indicate anout-of-phase condition. Altemately, an out-of-phase condition may beindicated on a meter arranged in parallel with an alarm.

CIGARETTE-DENSE-END-MEASURING METHOD AND APPARATUS This is acontinuation of my copending application Ser. No. 544,000, filed Apr.20, I966.

The present invention relates generally to cigarette makers and, moreparticularly, to a method and means for facilitating the manufactureofcigarettes having dense ends.

BACKGROUND Many cigarettes are being manufactured by providing extratobacco in the tobacco rod at the regions which will form the adjacentends of cut cigarettes. The purpose of this dense ending is to give thecigarette ends added firmness, good appearance and to prevent smallparticles of tobacco from falling out of loosely packed ends.

Dense-ending apparatuses are built into many modern cigarette machinesand they may take on various forms. For example, suction techniques maybe employed to drop increased amounts of tobacco onto the tobaccostream, compacting wheels may be used to compress the stream at variouspoints or a rotating trimmer disc having peripheral indentations may beused to trim off more tobacco in some regions of the stream than inothers. US. Pat. No. 3,032,041 issued to R. Lanore and British Patents813,576, 940,153, 941,852, and 948,736 are representative of the stateof the art in this area.

One problem that arises frequently with these systems is that the extratobacco in the cigarette rod may occur at the wrong location. The cutteris normally synchronized with the dense-ending device so that the cuttercuts through the rod substantially in the center of the dense regions.While the system may be initially set up to provide cigarettes havingsuitable dense ends, the cutter may be located several feet downstreamfrom the dense-ending device and the intervening rod forming mechanismsinduce an unpredictable stretching of the tobacco stream and cigaretterod causing misregistration of the cutter with the dense regions.Instead of occurring in the two butted adjacent cigarette ends where therod is cut, the dense regions may appear in the center of the cigarette.

Another problem concerns the amount of increased density added to thedense regions. Machines are commonly designed to put typically atpercent, a percent, or a percent increase in density into the ends ofthe cigarettes. Machine faults or maladjustments may cause the magnitudeof the dense regions of the tobacco rod to be less than desired.

PRIOR SYSTEMS It has been necessary to sample the density of a largenumber of cigarettes manually to determine whether or not the denseregions were of the desired magnitude and occurring at the ends of thecigarettes. When the production of faulty cigarettes was discovered, itwas necessary to stop the machine and adjust the dense-ending device.This method was not only time consuming but also wasteful, as a largenumber of objectionable cigarettes were produced as a result of thehigh-production rate, e.g. 1,800 cigarettes per minute or more, by onemachine, before the fault was discovered. Moreover, it was virtuallyimpossible to discriminate between a loss of cutter synchronization anda decrease in density of the dense regions.

BRZEF DESCRIPTION OF THE PRESENT INVENTION I provide a system fordetermining when a machine is producing cigarettes having acceptabledense ends and a method for controlling it to maintain the desiredcutter-dense end relationship. I use a gauge to provide a signalcontinuously proportional to the density or weight per unit length ofthe cigarette rod. A reference signal is obtained whenever the cuttercuts the cigarette rod. In one embodiment, I display the density signalsimultaneously with the reference signal to indicate whether or not thecutter is synchronized and cutting through the dense regions. Themachine may be adjusted to cut substantially through the center of eachdense region to provide a continuous supply of dense end cigarettes. Animprovement of this technique is the subject of a copending applicationSer. No. 543,916 filed Apr. 20, 1966 by Alan Norwich and John Dewitt andassigned to the same assignee as the present application.

In another embodiment, I sample the density of the ends of the cigaretteand adjust the machine to maximize the difference between the density atthe ends and the density of the remainder of the cigarette. Morespecifically, I partition the density signal into two components: afirst signal component represents the density of the segments of thetobacco rod which will form the ends of the cut cigarettes; the secondsignal component represents the density substantially of the remainderof the cigarette red. I compare the first component with the secondcomponent to determine when the dense regions are of the correct densityand occurring in synchronism with the cutter. When, for example, thedifference between the two signal components is the greatest, the denseregions of the rod are being separated by the cutter. l also provide analarm system to warn operating personnel of faulty dense end production.

BRIEF DESCRIPTION OF THE OBJECTS Accordingly, it is a primary object ofthe present invention to provide a method and apparatus for continuouslymeasuring and indicating the position of dense regions in a tobacco rodrelative to the cutter in a cigarette-making machine.

It is also an object of the present invention to provide adense-end-monitoring system that eliminates time-consuming manualsampling.

It is another object of the present invention to, provide adense-end-monitoring system that responds not only to misregistration ofthe cutter but also to a deficient density condition with the furthercapability of being able to discriminate between these two causes offaulty dense ends.

It is still another object of the present invention to provide animproved method for controlling a cigarette machine to provide acontinuous supply of dense end cigarettes.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a block diagram illustratinga cigarette-dense-endmachine-monitoring system, together with threeassociated graphs of typical waveforms depicting signal amplitudes as afunction of time t;

FIG. 2 is a graph of cigarette rod density vs. time for two cigarettesamples;

FIG. 3 is a plot of the magnitude of the output difference signal vs.phase angle between the cutter and the dense-ending mechanisms; and,

FIG. 4 is a diagrammatic view of one type of visual readout of dense endcondition.

CIGARETTE DENSE END PROCESS With reference now to the drawings andparticularly to FIG. 1, a cigarette making process includes a tobaccostream former it) delivering a stream 12 of tobacco to a rod former l4.Rod former l4 wraps a paper strip to around the tobacco stream l2 andglues the seam to form a cigarette rod 18. The cigarette rod is conveyedto a cutter 20 which periodically cuts a cigarette 22 of length L fromthe continuous rod 18. In the past, this type of industrial process hasbeen measured and controlled to provide cigarettes having a desiredweight per unit length. For a more detailed description of thecigarettemaking machine, reference may be had to US. Reissue Pat. Re.25,476 issued Nov. 12, I963 to S. A. Radley et al. and assigned to thesame assignee as the present invention.

Some machines are equipped with a dense end device 24 which may comprisea rotating trimmer disc having raised portions spaced around theperiphery thereof. Other devices may be employed to provide the samefunction; some of these are described in the patents cited, supra. Thedisc trims off some tobacco 12a from the stream 12 to form a streamhaving dense regions R spaced one cigarette length L apart from oneanother. The density of the tobacco in the dense regions R of thetrimmed stream or cigarette rod 18 may be up to 20 percent greater thanthe density in the remainder of the trimmed stream or the rod 18. In atypical example, the length AL of the dense region may be to mm. inlength while the entire cigarette may be some 70 mm. in length.

A main drive motor 26 provides the motive power for simultaneouslyconveying the cigarette rod 18 toward the cutter 20 and actuating thecutter 20 to cut cigarettes of substantially equal length from the rod18. The dense end device 24 is also coupled to the main drive motor 26as indicated by the dotted line 28. The object is to time the cutteroperation with the dense end device 24 so that the cutter 20 cuts thetobacco rod 18 substantially in the center of each dense region R. If,due to longitudinal dimensional changes of the rod 18 or slippage of thedrive to either the cutter 20 or the dense end trimmer, the cutter anddense regions R are not in synchronism, the cigarettes 22 will eitherhave an insufficient amount of tobacco at one end or the other or nodense ends at all.

This effect is graphically shown in FIG. 2 wherein a density profile 27is plotted on the same time scale as pulses 29 occurring when the cutter20 cuts through the tobacco rod. A superposed cigarette 22 is shown insection to illustrate an acceptable dense end condition (Case I) and anobjectionable dense end condition (Case ll). In both cases, the locationof the ends of the cigarettes 22 are in time coincidence with the cutterpulses 29. In Case I, however, the dense regions R arrive at the cutter20 when a cigarette is being cut. Cigarettes are provided with dense endportions. Case ll illustrates a situation where the dense regions Rarrive at the cutter 20 several milliseconds late so that the cutcigarettes contain a centrally located dense portion.

DESCRIPTION OF THE PRESENT INVENTION To provide cigarettes having endsof the desired density, I continuously monitor the density of thecigarette rod 18 and determine when the dense regions R appear at thecutter. A density gauge 30 such as a capacitance gauge or a nuclearradiation gauge is positioned preferably a short distance upstream andas near as physically possible to the cutter 20.

A pair of gates 32 and 34 receive the output signal from the gauge 30and route the signal alternately into two separate paths. During part ofthe time the signal is transmitted only along a first path through gate32. During the remainder of the time the signal is transmitted onlyalong a second path through gate 34. The operation of the gates is timedso that gate 32 transmits the time-selected component of the gaugesignal with is responsive to the density of the cigarette rod 18 in theregion where it is cut by the cutter 20. The timing is also such thatgate 34 transmits the other component of the gauge signal which isresponsive to the density of the cigarette rod in the central regionsthereof between the cut ends of the cigarettes made from the rod.

The gates 32 and 34 are controlled by pulse signals from a cutter pulsegenerator 36 coupled to the cutter 29 to generate a pulse train 38.Pulse train 38 includes pulses occurring as every cigarette 22 is cut.The on-time T of the pulse 38 may be of any duration, but it ispreferably fixed in accordance with the time of transport of the typicallength, AL, of each dense region past a given point such as the densitygauge 30. The pulses 38 can be generated, for example, by cam-actuatedlimit switches or by a photocell receiving light reflected off asegmental reflecting portion of a rotating cutter axle or hub. Themechanical connection between the cutter pulse generator 36 and thecutter 20 is represented by the dotted line 40. Gate 32 is opened by thepulses in the cutter pulse train 33 for the time T,. Gate 34 is closedduring this time. Gate 32 is closed for the time T and gate 34 is openedfor this period. In a simple form, gates 32 and 34 could comprise asingle-pole double-throw switch actuated by the cutter mechanism in anarrangement similar to that illustrated and described in U.S. Pat. No.2,357,860 issued Sept. 12, 1944 to U. A. Whitaker or in U.S. Pat. No.2,999,520 issued Sept. I2, 1961 to W. B. Lowman.

it may be desirable to mount the density gauge 30 a known distance, suchas an integral number of cigarette lengths, nL, away from the cutter 20so that when one dense region is being measured by the gauge 30, aprevious one is located at the cutter 20. in this case the delay unit 31may be omitted, as indicated by the dotted line showing the same. Inthose cases where the gauge 30 introduces an inherent lag in measuringthe density of the cigarette rod 18 that is large with respect to thetime of transport of one cigarette length L past a given point, it maybe necessary to delay the cutter signal for this period to insure thatonly those portions of the gauge signals representing the density of thesegments of rod 18 destined to form the ends of the cigarettes 22 areselected for transmission by the gate 32. Alternatively, the gaugesignal itself may be delayed by a delay unit 31 to insure the desiredtime correspondence of the periodic closing of gate 32. Since any onedense region R is ordinarily subdivided between one cigarette 22 and thenext, the cutter pulse generator 36 is adjusted to provide cutter pulses38 that start slightly in advance of each stroke of the cutter 20, sothat the portion of the gauge signal passing through the gate 32 duringa given opening thereof represents a cigarette rod portion includingequal lengths of the trailing part of one cigarette and the leading partof the succeeding cigarette. When the various delays are accounted for,only the density of the ends of the cigarettes is being indicated by theportion of the density gauge signal transmitted by the gate 32.

The gates 32 and 34 thus deliver signals S, and S having the waveformsshown. The signal S represents the variations in the density of thatportion of the cigarette rod 18 including a part immediately before anda part immediately after the location where it is cut by the cutter 20.The density variations appear for only a relatively short period of timeT, and are representative of that portion of the cigarette rod 18 whichforms the butted ends of adjacent cigarettes. The signal S representsthe variations in the density of the remaining central portion of eachcigarette 22. The magnitude of signal S is generally smaller than themagnitude of signal S,.

The average value of signals S and S are computed by a pair of averagingcircuits 42 and 44. A difference computer 46 provides an output signal Sthe magnitude of which can be read out on a meter 48. The signal S isproportional to the difference between the averaged values of signals Sand S OPERATION OF THE PRESENT lNVENTlON If the density gauge is spaced2. distance nL upstream from the cutter, dense regions R will occursimultaneously at the density gauge 30 and at the cutter 20. If a denseregion is detected by the gauge 3t) at the same time cutter 20 iscutting through the cigarette rod 18 the signal 8,, will be relativelylarge. The signal S being representative of the density of the central,less dense area of the cigarettes 22, will be less. The differencesignal S reaches a maximum value graphically indicated in MG. 3indicating exact synchronization of the cutter 2% with the dense-endingdevice 24.

Should the dense regions R of the cigarette rod 18 for one reason oranother, leg or lead relative to the cutter 20, some of the measuredincreased density will appear in signal S increasing its average value.Similarly, the average value of signal S will decrease due to thedecrease in measured density for the end segment portions of thecigarette rod 13. The result is a significant decrease in the difierencesignal S Any change in the indication of meter 43 from maximumdeflection may be indicative of a faulty dense end condition. Thus,according to the method of the present invention, operating personnel,by observing the face of meter 48, are immediately advised of anydeterioration in machine performance so that suitable correction can bemade to produce continuously cigarettes having acceptable dense ends.

The signal comparison technique provides a way to check the magnitude ofthe density of the dense regions against that of the remaining portionof the cigarettes. Therefore, if the average weight of the cigarettesfalls below a specification or target weight, my system will stilldetermine the relative magnitude difference and indicate whenobjectionable dense end cigarettes are being produced.

As mentioned above, a machine malfunction may result in a reduction inthe density of the dense regions R. Such a reduction causes a decreasein the magnitude of signals S and S even though cutter synchronizationis maintained. As a check, I provide a deviation analyzer that can beused to affirm or reject cutter synchronization as a cause of a downwarddeflection of the indication on meter 48.

DEVIATION ANALYZER Referring to FIG. 4, the density gauge 30 preferablycomprises a radiation source 52 and a detector 54 positioned on oppositesides of the cigarette rod 18. The density functional signal derived bythe detector 54 is transmitted to a visual indicator such asoscilloscope 56 along with the pulse train provided by a cutter pulsegenerator 36. Again, in some cases, it may be necessary to delay thedensity signal by means of a delay unit 59. The two signals may bedisplayed instead on a fast chart recorder such as is marketed byHoneywell, Inc., under the Trade Mark, VISICORDER, and described in US.Pat. No. 2,580,427. The two signals are separately coupled into verticaldeflection channels A and B of the oscilloscope 56. The cutter pulsescan be used to trigger the horizontal sweep of the oscilloscope. Theresult is a graphical display of a trace 60 representative of thedensity of the cigarette rod 18 in time coincidence with a trace 62representative of the cutter pulses. Operating personnel are visuallyadvised of the amount and direction of any deviation in cuttersynchronization by observing the lateral shift in the cutter pulserelative to the dense end peaks in the density trace 60. When the cutterpulse is vertically aligned with the density peaks representative of thedense regions R, the cutter is fully synchronized. The amount of timelead or lag can be estimated from the distance between the dotted lines66 for the purpose of controlling the process according to the method ofthe present invention, to maintain the desired cutter synchronization.

Instead of equipping each cigarette machine in a plant with an analyzer,I provide a simple alarm system on each machine to warn of a faultydense end condition (see FIG. 1 An alarm 70 which may be a buuer or aflashing light is energized when a signal comparator 72, comparing themagnitude of the difference signal S with that of a reference signalfrom a generator 74, finds that the difference signal has dropped belowthe threshold shown in dotted lines in FIG. 3. The magnitude of thereference signal is selectable by a control knob 75, since thedifference signal magnitude will depend on how much extra density agiven machine is designed to put into the dense regions R of thecigarette rod 13.

An alarm indication may call for investigation of the machine byoperating personnel. My deviation analyzer (FIG. 4) can be made portableand rolled up to the faulty machine in response to an alarm indication.As is well known, each cigarette machine is ordinarily equipped with agauge 30, arranged so that a strip chart recorder or portable processanalyzer can be temporarily plugged in via the usual jack, and a similarjack can be provided for the connection of the oscilloscope 56 and/ordelay unit 59. Similarly, each machine may have the photocell detectoror limit switch of the cutter pulse generator 36 permanently mounted andequipped with a suitable jack. Synchronization can then be quicklychecked by routing the density gauge signal and the cutter pulsesdirectly into the oscilloscope 56. If the cutter pulses of trace 62 lineup with the dense end pulses of trace 60, it is at once apparent to theoperator that the alarm indication was not caused by a lack of cuttersynchronization, but was the result of some other mechanical malfunctionsuch as would cause starving of the tobacco supply to the dense regionsR.

ALTERNATIVE EMBODIMENTS While a dual density signal comparison circuitis shown and described, it has particular utility on lines where theaverage weights of the cigarettes wander from the desired specificationon target value. If this is not the case, the magnitude of the signal Salone can be processed to determine whether or not the desired dense endcondition is being maintained. The alternate signal channel does,however, also provide one with a source from which the average weight ofcigarettes (minus the dense ends) can be readout.

My system also provides a method for controlling thecigarette-dense-ending process of FIG. 1. One may manually adjust therelative position of the dense end device 24 and the cutter 20 inresponse to a downward deflection of the indication of meter 48. Thismay be done by stopping the machine and rotating the trimmer discslightly while maintaining the position of the cutter, by altering thespacing between the two units or by other means more suited to the typeof machine being monitored. Alternatively, a differential gearing unit76 (see FIG. 1) can be adjusted through a servo unit 78. Thedifferential unit 76 may have a pair of output shafts 80 and 82, drivenby the main drive motor 26 and having a speed ratio of adjustablemagnitude. Shafts 80 and 82 may be coupled to the cutter 20 and thedense end device 24, respectively. Servo 78 can be coupled to the ratioadjusting member of the differential 76 as indicated by the heavy dottedline 84 and actuated from a remote location.

Alternatively, the differential 76 or other mechanical drive expedientscan be manually adjusted by operating personnel observing the face ofthe oscilloscope 56 (FIG. 4). The advantage of this type of data readoutover that provided by the meter 48 is that one can see immediately inwhich direction correction must be initiated to establish the desiredsynchronization.

Although certain specific embodiments of the invention have been shownand described herein, many modifications may be made thereto withoutdeparting from the true spirit and scope of the invention as set forthin the appended claims.

What is claimed is:

l. The method of monitoring the operation of a machine for producingcigarettes having dense ends, said machine having means for forming acontinuous tobacco rod containing extra tobacco in locally dense regionsuniformly spaced along its length and means for conveying said rod alonga path including the location of a cutter for providing a plurality ofcigarettes cut from said rod, said method comprising the steps of:

measuring the density of said rod as it passes a point along said pathto produce a first signal having a recurrent dense region indicatingsignal portion responsive to said dense regions and another signalportion responsive to other regions in said tobacco rod,

generating a recurrent reference signal in response to the operation ofsaid cutter, and

comparing the phase of said reference signal with the phase of one ofsaid first signal portions to provide a quantitative indication of thedistance along the rod between the position of said dense regions andthe ends of the cut cigarettes.

2. The method of monitoring the operation of a machine for producingcigarettes having dense ends, said machine having means for forming acontinuous tobacco rod having locally relatively dense regions uniformlyspaced along its length and means for conveying said rod along a pathincluding the location of a cutter for providing a plurality ofcigarettes cut from said rod, said method comprising the steps of:

measuring the density ofsai fod affixed location along said path beforethe rod is cut by said cutter to produce a first signal having arecurrent dense region indicating signal portion responsive to thepassage of said dense regions and another signal portion responsive tothe passing of other regions in said tobacco rod,

delaying said first signal to provide a measure of the density of saidtobacco rod occurring at said cutter when said rod is cut,

generating a recurrent reference signal in response to the operation ofsaid cutter, and

comparing the phase of said reference signal with the phase of one ofsaid first signal portions in said delayed first signal to indicate theposition of said dense regions rela tive to the ends of said outcigarettes.

3. The method of monitoring the operation of a cigarettemaking machinehaving a cutter providing a plurality of cigarettes from a continuousrod of tobacco moving relative to said cutter and having locally denseregions spaced along said tobacco rod, said method comprising the stepsof:

continuously measuring the density of said tobacco rod occurring inadvance of said cutter,

generating a signal whenever said cutter cuts through said tobacco rod,and

displaying said density measurement and said generated signal tovisually determine the position along the rod of each of said locallydense regions relative to the ends of said cut cigarettes.

4. The method of monitoring the operation of a cigarettemaking machinehaving a cutter providing a plurality of cigarettes cut from acontinuous rod moving relative to said cutter and having locally denseregions spaced along said cigarette rod by a dense end device, saidmethod comprising the steps of:

continuously measuring the density of said cigarette rod,

partitioning said continuous density measurement into a first componentrepresenting the density of the segments of said cigarette rod whichwill form the ends of said cut cigarettes and a second componentrepresenting the density of the remainder of said cigarette rod, and

comparing said first density component with said seconddensity componentto determine when said end segments include said locally dense regions.

5. The method of claim 4 which further includes the step of:

adjusting the relative position of said cutter and said dense end deviceto maximize the magnitude of said first density component so that eachof said locally dense regions of said cigarette rod is included in thebutted ends of two adjacent cigarettes.

6. The method of synchronizing the operation of the cutting mechanismand the denseend-forming means of a cigarettemaking machine providing aplurality of cigarettes cut from a continuous cigarette rod movingrelative to said cutter mechanism and having locally dense regionsspaced along said cigarette rod, said method comprising the steps of:

measuring the density of said cigarette rod before it is cut by saidcutting mechanism,

selecting portions of said density measurement at time intervalssynchronized with said cutting mechanism,

averaging said selected portions to obtain a first signal,

averaging other portions of said density measurement to obtain a secondsignal, comparing said first signal with said second signal to obtain adifference signal, and

producing an indication in response to said difference signal that saidcutting mechanism is cutting said cigarette rod substantially in thecenter of each of said locally dense regions.

7. The method of synchronizing the operation of the cutting mechanismand the dense-end-forming means of a cigarettemaking machine providing aplurality of cigarettes from a continuous rod moving relative to saidcutting mechanism and having locally dense regions substantially equallyspaced along said cigarette rod by said dense end forming means, saidmethod comprising the steps of:

measuring the density of said cigarette rod at an inspection station,

selecting portions of said density measurement at time intervalssynchronized with said cutting mechanism,

averaging said selected density measurement portions to obtain a firstsignal,

averaging the remaining portions of said density measurement occurringat other time intervalsto obtain a second signal, comparing said firstsignal with said second signal to obtain a difference signal, and

adjusting the relative positions of said cutting mechanism and saiddense end former to maximize said difference signal and providecigarettes having a portion of said locally dense regions located ateach end of each of said cigarettes.

8. Apparatus for synchronizing a cutting mechanism and adense-endforrning means in a cigarette-making machine providing acontinuous traveling rod having locally dense regions spaced along thelength thereof, said apparatus comprismg:

means for continuously measuring the density of said cigarette rodupstream from said cutter,

means for generating a signal having a pulse whenever said cutter cutsthrough said cigarette rod, and

means for receiving and simultaneously displaying said densitymeasurement and said generated pulse to visually indicate the positionof said locally dense regions relative to the ends of said cutcigarettes.

9. Apparatus for monitoring the operation of a cigarettemaking machinehaving a cutter providing a plurality of cigarettes cut from acontinuous rod moving relative to said cutter and having locally denseregions spaced .along said tobacco rod, said apparatus comprising:

means for continuously measuring the density of said cigarette rod,

means for partitioning said continuous density measurement into a firstcomponent representing the density of the segments of said cigarette rodwhich will form the ends of said out cigarettes and a second componentrepresenting the density of another part of said cigarette rod, and

means for comparing said first density component with said seconddensity component to determine when said end segments include saidlocally dense regions.

10. Apparatus for a cigarette-making machine providing a continuoustraveling rod having locally dense regions spaced along the lengththereof and including a cutter for cutting individual cigarettes fromsaid traveling rod, said apparatus comprising:

means for measuring the average density of said cigarette rod in theregions thereof where the rod is to be cut by said cutter,

means for measuring the average density of other regions of saidcigarette rod,

means for comparing said average density measurements to obtain adifference signal, and

means for utilizing said difference signal to indicate when said cutteris cutting substantially in the center of each of said locally denseregions. 11. Apparatus for a cigarette-making machine providing acontinuous traveling rod having locally dense regions spaced along thelength thereof and including a cutter for cutting individual cigarettesfrom said traveling rod, said apparatus comprising:

means for continuously measuring the density of said continuouscigarette rod in the vicinity of said cutter mechanism and developing asignal in response thereto,

means for generating a signal having a pulse substantially at the sametime said cutter passes through said cigarette rod, and

means for graphically displaying said density signal and said cutterpulse signal simultaneously to determine the phase relationship betweensaid cutter operation and the occurrence of said locally dense regionsof said cigarette rod at said cutter. 12. Apparatus for synchronizingthe operation of the cutter of the knife mechanism of a cigarette-makingmachine and a dense end former providing a plurality of cigarettes cutfrom a continuous traveling rod having locally dense regions spacedalong said rod by said rotating dense end former, said apparatuscomprising:

a radiation gauge for measuring the density of the rod and for providingan output signal proportional thereto in the vicinity of said cutter,gate means actuated by said knife mechanism for partitioning said outputsignal including a first gate passing for a fixed period of time aportion of said output signal representative of the density of saidcigarette rod in the vicinity of said cutter and a second gate passingthe remaining portion of said radiation gauge output signal,

signal-averaging means for averaging the value of each of said signalspassed by said first and second gate,

means providing a third signal proportional to the difference betweensaid averaged gate signals, and

means responsive to said third signal for indicating the position ofsaid locally dense regions relative to the ends of said out cigarettes.

13. Apparatus as set forth in claim 12, in which said means responsiveto said third signal includes:

an alarm, and

means for energizing said alarm whenever the magnitude of saiddifference signal falls below a predetermined minimum level.

14. Apparatus for monitoring the operation of a machine for producingcigarettes having dense ends, said machine having means for forming acontinuous tobacco rod having locally relatively dense regions uniformlyspaced along its length and means for conveying said rod along a pathincluding the location of a cutter for providing a plurality ofcigarettes cut from said rod, said apparatus comprising:

means for measuring the density of said rod as it passes a point alongsaid path to produce a first signal having a recurrent dense regionindicating signal portion responsive to said dense regions and anothersignal portion responsive to other regions in said tobacco rod,

means for generating a recurrent reference signal in response to theoperation of said cutter, and

means for comparing the phase of said reference signal with the phase ofone of said first signal portions to provide a quantitative indicationof the distance between the position of said dense regions and the endsof the cigarettes.

15. A method for controlling a machine for producing cigarettes havingdense ends, said machine having means including a dense end device forforming a continuous tobacco rod having locally relatively dense regionsuniformly spaced along its length and means for conveying said rod alonga path including the location of a cutter for providing a plurality ofcigarettes cut from said rod, comprising the steps of:

measuring the density of said rod as it passes a point along said pathto produce a first signal having a recurrent dense region indicatingsignal portion responsive to said dense regions and another signalportion responsive to other regions in said tobacco rod,

generating a recurrent reference signal in response to the operation ofsaid cutter, and '4 adjusting the relative speed of operation of saiddense end device and said cutter in response to the relative phases ofsaid reference signal and one of said first signal portions. 16.Apparatus for monitoring the operation of a cigarettemaking machinehaving a cutter providing a plurality of cigarettes cut from acontinuous rod of tobacco moving relative to said cutter and havinglocally dense regions spaced along said tobacco rod by a dense enddevice, said apparatus comprising:

means responsive to the density of said tobacco rod as it moves towardsaid cutter for producing a signal having a dense region indicatingsignal portion responsive to said dense regions and another signalportion responsive to other regions in said tobacco rod,

means for measuring the phase relationship between the operation of saidcutter to out said rod and the occurrence of said dense regionindicating signal portions to provide a signal which is a function ofthe deviation of the position of said dense regions from the ends ofsaid cut cigarettes.

17. Apparatus for monitoring the operation of a cigarettemaking machinehaving a cutter providing a plurality of cigarettes cut from acontinuous rod moving relative to said cutter and having locally denseregions spaced along said tobacco rod by a dense end device, saidapparatus comprising:

means for generating a first signal whenever one of said dense regionsshould occur at said cutter,

means for generating a second signal whenever said cutter cuts acigarette from said rod, and

means for continuously comparing the phase of said first signal relativeto said second signal to determine the relative degree ofsynchronization between said cutter and said dense regions occurringthereat.

18. Apparatus for monitoring the operation of a cigarettemaking machinehaving a cutter providing a plurality of cigarettes cut from acontinuous rod of tobacco moving relative to said cutter and havinglocally dense regions spaced along said tobacco rod by a dense enddevice, said apparatus comprising:

means for continuously measuring the density of said cigarette rod toprovide a signal having a periodic increased portions corresponding tosaid dense regions of said rod as they should occur at said cutter,

means coupled to said cutter to provide a reference pulse whenever acigarette is cut from said cigarette rod,

phase detector means for measuring a phase difference of said measuredincreased density portions from said reference pulses, and

means for utilizing said measured phase difference to indicate adeviation of said dense regions from the ends of said out cigarettes.

19. Apparatus for monitoring the operation of a cigarettemaking machinehaving a cutter providing a plurality of cigarettes cut from acontinuous rod of tobacco moving relative to said cutter and havinglocally dense regions spaced along said rod, said apparatus comprising:

means for continuously measuring the density of said tobacco rod toproduce a density signal,

means responsive to the operation of said cutter as it cuts said rod forproducing a second signal, and

means for displaying said measured density signal and said second signalto indicate the position of said dense regions relative to the ends ofsaid cigarettes.

1. The method of monitoring the operation of a machine for producingcigarettes having dense ends, said machine having means for forming acontinuous tobacco rod containing extra tobacco in locally dense regionsuniformly spaced along its length and means for conveying said rod alonga path including the location of a cutter for providing a plurality ofcigarettes cut from said rod, said method comprising the steps of:measuring the density of said rod as it passes a point along said pathto produce a first signal having a recurrent dense region indicatingsignal portion responsive to said dense regions and another signalportion responsive to other regions in said tobacco rod, generating arecurrent reference signal in response to the operation of said cutter,and comparing the phase of said reference signal with the phase of oneof said first signal portions to provide a quantitative indication ofthe distance along the rod between the position of said dense regionsand the ends of the cut cigarettes.
 2. The method of monitoring theoperation of a machine for producing cigarettes having dense ends, saidmachine having means for forming a continuous tobacco rod having locallyrelatively dense regions uniformly spaced along its length and means forconveying said rod along a path including the location of a cutter forproviding a plurality of cigarettes cut from said rod, said methodcomprising the steps of: measuring the density of said rod at fixedlocation along said path before the rod is cut by said cutter to producea first signal having a recurrent dense region indicating signal portionresponsive to the passage of said dense regions and another signalportion responsive to the passing of other regions in said tobacco rod,delaying said first signal to provide a measure of the density of saidtobacco rod occurring at said cutter when said rod is cut, generating arecurrent reference signal in response to the operation of said cutter,and comparing the phase of said reference signal with the phase of oneof said first signal portions in said delayed first signal to indicatethe position of said dense regions relative to the ends of said cutcigarettes.
 3. The method of monitoring the operation of acigarette-making machine having a cutter providing a plurality ofcigarettes from a continuous rod of tobacco moving relative to saidcutter and having locally dense regions spaced along said tobacco rod,said method comprising the steps of: continuously measuring the densityof said tobacco rod occurring in advance of said cutter, generating asignal whenever said cutter cuts through said tobacco rod, anddisplaying said density measurement and said generated signal tovisually determine the position along the rod of each of said locallydense regions relative to the ends of said cut ciGarettes.
 4. The methodof monitoring the operation of a cigarette-making machine having acutter providing a plurality of cigarettes cut from a continuous rodmoving relative to said cutter and having locally dense regions spacedalong said cigarette rod by a dense end device, said method comprisingthe steps of: continuously measuring the density of said cigarette rod,partitioning said continuous density measurement into a first componentrepresenting the density of the segments of said cigarette rod whichwill form the ends of said cut cigarettes and a second componentrepresenting the density of the remainder of said cigarette rod, andcomparing said first density component with said second densitycomponent to determine when said end segments include said locally denseregions.
 5. The method of claim 4 which further includes the step of:adjusting the relative position of said cutter and said dense end deviceto maximize the magnitude of said first density component so that eachof said locally dense regions of said cigarette rod is included in thebutted ends of two adjacent cigarettes.
 6. The method of synchronizingthe operation of the cutting mechanism and the dense-end-forming meansof a cigarette-making machine providing a plurality of cigarettes cutfrom a continuous cigarette rod moving relative to said cutter mechanismand having locally dense regions spaced along said cigarette rod, saidmethod comprising the steps of: measuring the density of said cigaretterod before it is cut by said cutting mechanism, selecting portions ofsaid density measurement at time intervals synchronized with saidcutting mechanism, averaging said selected portions to obtain a firstsignal, averaging other portions of said density measurement to obtain asecond signal, comparing said first signal with said second signal toobtain a difference signal, and producing an indication in response tosaid difference signal that said cutting mechanism is cutting saidcigarette rod substantially in the center of each of said locally denseregions.
 7. The method of synchronizing the operation of the cuttingmechanism and the dense-end-forming means of a cigarette-making machineproviding a plurality of cigarettes from a continuous rod movingrelative to said cutting mechanism and having locally dense regionssubstantially equally spaced along said cigarette rod by said dense endforming means, said method comprising the steps of: measuring thedensity of said cigarette rod at an inspection station, selectingportions of said density measurement at time intervals synchronized withsaid cutting mechanism, averaging said selected density measurementportions to obtain a first signal, averaging the remaining portions ofsaid density measurement occurring at other time intervals to obtain asecond signal, comparing said first signal with said second signal toobtain a difference signal, and adjusting the relative positions of saidcutting mechanism and said dense end former to maximize said differencesignal and provide cigarettes having a portion of said locally denseregions located at each end of each of said cigarettes.
 8. Apparatus forsynchronizing a cutting mechanism and a dense-end-forming means in acigarette-making machine providing a continuous traveling rod havinglocally dense regions spaced along the length thereof, said apparatuscomprising: means for continuously measuring the density of saidcigarette rod upstream from said cutter, means for generating a signalhaving a pulse whenever said cutter cuts through said cigarette rod, andmeans for receiving and simultaneously displaying said densitymeasurement and said generated pulse to visually indicate the positionof said locally dense regions relative to the ends of said cutcigarettes.
 9. Apparatus for monitoring the operation of acigarette-making machine having a cutter providing a plurality ofcigarettes cut from a continuous rod moving relative to said cutter andhaving locally dense regions spaced along said tobacco rod, saidapparatus comprising: means for continuously measuring the density ofsaid cigarette rod, means for partitioning said continuous densitymeasurement into a first component representing the density of thesegments of said cigarette rod which will form the ends of said cutcigarettes and a second component representing the density of anotherpart of said cigarette rod, and means for comparing said first densitycomponent with said second density component to determine when said endsegments include said locally dense regions.
 10. Apparatus for acigarette-making machine providing a continuous traveling rod havinglocally dense regions spaced along the length thereof and including acutter for cutting individual cigarettes from said traveling rod, saidapparatus comprising: means for measuring the average density of saidcigarette rod in the regions thereof where the rod is to be cut by saidcutter, means for measuring the average density of other regions of saidcigarette rod, means for comparing said average density measurements toobtain a difference signal, and means for utilizing said differencesignal to indicate when said cutter is cutting substantially in thecenter of each of said locally dense regions.
 11. Apparatus for acigarette-making machine providing a continuous traveling rod havinglocally dense regions spaced along the length thereof and including acutter for cutting individual cigarettes from said traveling rod, saidapparatus comprising: means for continuously measuring the density ofsaid continuous cigarette rod in the vicinity of said cutter mechanismand developing a signal in response thereto, means for generating asignal having a pulse substantially at the same time said cutter passesthrough said cigarette rod, and means for graphically displaying saiddensity signal and said cutter pulse signal simultaneously to determinethe phase relationship between said cutter operation and the occurrenceof said locally dense regions of said cigarette rod at said cutter. 12.Apparatus for synchronizing the operation of the cutter of the knifemechanism of a cigarette-making machine and a dense end former providinga plurality of cigarettes cut from a continuous traveling rod havinglocally dense regions spaced along said rod by said rotating dense endformer, said apparatus comprising: a radiation gauge for measuring thedensity of the rod and for providing an output signal proportionalthereto in the vicinity of said cutter, gate means actuated by saidknife mechanism for partitioning said output signal including a firstgate passing for a fixed period of time a portion of said output signalrepresentative of the density of said cigarette rod in the vicinity ofsaid cutter and a second gate passing the remaining portion of saidradiation gauge output signal, signal-averaging means for averaging thevalue of each of said signals passed by said first and second gate,means providing a third signal proportional to the difference betweensaid averaged gate signals, and means responsive to said third signalfor indicating the position of said locally dense regions relative tothe ends of said cut cigarettes.
 13. Apparatus as set forth in claim 12,in which said means responsive to said third signal includes: an alarm,and means for energizing said alarm whenever the magnitude of saiddifference signal falls below a predetermined minimum level. 14.Apparatus for monitoring the operation of a machine for producingcigarettes having dense ends, said machine having means for forming acontinuous tobacco rod having locally relatively dense regions uniformlyspaced along its length and means for conveying said rod along a pathincluding the location of a cutter for providing a plurality ofcigarettes cut from said rod, said apparatus compriSing: means formeasuring the density of said rod as it passes a point along said pathto produce a first signal having a recurrent dense region indicatingsignal portion responsive to said dense regions and another signalportion responsive to other regions in said tobacco rod, means forgenerating a recurrent reference signal in response to the operation ofsaid cutter, and means for comparing the phase of said reference signalwith the phase of one of said first signal portions to provide aquantitative indication of the distance between the position of saiddense regions and the ends of the cigarettes.
 15. A method forcontrolling a machine for producing cigarettes having dense ends, saidmachine having means including a dense end device for forming acontinuous tobacco rod having locally relatively dense regions uniformlyspaced along its length and means for conveying said rod along a pathincluding the location of a cutter for providing a plurality ofcigarettes cut from said rod, comprising the steps of: measuring thedensity of said rod as it passes a point along said path to produce afirst signal having a recurrent dense region indicating signal portionresponsive to said dense regions and another signal portion responsiveto other regions in said tobacco rod, generating a recurrent referencesignal in response to the operation of said cutter, and adjusting therelative speed of operation of said dense end device and said cutter inresponse to the relative phases of said reference signal and one of saidfirst signal portions.
 16. Apparatus for monitoring the operation of acigarette-making machine having a cutter providing a plurality ofcigarettes cut from a continuous rod of tobacco moving relative to saidcutter and having locally dense regions spaced along said tobacco rod bya dense end device, said apparatus comprising: means responsive to thedensity of said tobacco rod as it moves toward said cutter for producinga signal having a dense region indicating signal portion responsive tosaid dense regions and another signal portion responsive to otherregions in said tobacco rod, means for measuring the phase relationshipbetween the operation of said cutter to cut said rod and the occurrenceof said dense region indicating signal portions to provide a signalwhich is a function of the deviation of the position of said denseregions from the ends of said cut cigarettes.
 17. Apparatus formonitoring the operation of a cigarette-making machine having a cutterproviding a plurality of cigarettes cut from a continuous rod movingrelative to said cutter and having locally dense regions spaced alongsaid tobacco rod by a dense end device, said apparatus comprising: meansfor generating a first signal whenever one of said dense regions shouldoccur at said cutter, means for generating a second signal whenever saidcutter cuts a cigarette from said rod, and means for continuouslycomparing the phase of said first signal relative to said second signalto determine the relative degree of synchronization between said cutterand said dense regions occurring thereat.
 18. Apparatus for monitoringthe operation of a cigarette-making machine having a cutter providing aplurality of cigarettes cut from a continuous rod of tobacco movingrelative to said cutter and having locally dense regions spaced alongsaid tobacco rod by a dense end device, said apparatus comprising: meansfor continuously measuring the density of said cigarette rod to providea signal having a periodic increased portions corresponding to saiddense regions of said rod as they should occur at said cutter, meanscoupled to said cutter to provide a reference pulse whenever a cigaretteis cut from said cigarette rod, phase detector means for measuring aphase difference of said measured increased density portions from saidreference pulses, and means for utilizing said measured phase differenceto indicate a deviation of saId dense regions from the ends of said cutcigarettes.
 19. Apparatus for monitoring the operation of acigarette-making machine having a cutter providing a plurality ofcigarettes cut from a continuous rod of tobacco moving relative to saidcutter and having locally dense regions spaced along said rod, saidapparatus comprising: means for continuously measuring the density ofsaid tobacco rod to produce a density signal, means responsive to theoperation of said cutter as it cuts said rod for producing a secondsignal, and means for displaying said measured density signal and saidsecond signal to indicate the position of said dense regions relative tothe ends of said cigarettes.